This application claims the priority of German Application No. 199 02 638.6, filed Jan. 23, 1999, the disclosure of which is expressly incorporated by reference herein.
The invention relates to a process performed when starting an engine of a vehicle equipped with an automated or automatic transmission and a vehicle brake.
In vehicles having automated standard transmissions, the first gear is often engaged automatically to increase the roll-away resistance when the engine is switched off. This condition must then be eliminated when the vehicle is started because it would otherwise result in an unintentional movement of the vehicle. In such a case, the driver must first ascertain whether the neutral position has been selected or the transmission line has been interrupted. If this is not so, he must first select the neutral position or interrupt the transmission line. If he does not carry out this step, the engine cannot be started for safety reasons. However, if he does carry out this step, he must often operate the service brake for starting the engine in order to keep the vehicle from rolling away.
From German Patent document DE 196 32 863 A1, a motor vehicle is known having a parking brake, in which case, depending on the operating condition of the vehicle, a hydraulic or electro-mechanical operating mode can be selected. For example, when the vehicle is used, the vehicle brake is operated in the hydraulic mode and, after the driver has left the vehicle, it is operated in the electromechanical mode. A decision with respect to a change-over can take place based on a door operation, a driver seat occupation detection or a detection of an ignition activation. However, automatic operation of a brake, which was previously not operated, is not described.
In contrast, German Patent document 196 29 426 A1 describes an automated parking brake, in which case, after the end of the driving operation, the parking brake is automatically operated. However, when the driving operation is started, the parking brake is released again.
It is not possible with the above-mentioned devices and processes, however, to achieve a situation in which the vehicle is not secured by means of a vehicle brake (particularly a parking brake) while the vehicle is switched off, but nevertheless ensuring a secure starting of the vehicle.
It is therefor an object of the present invention to provide a simple process for increasing driving safety and operating comfort when starting an engine.
This object is achieved by a process to be performed when starting the engine of a vehicle with an automated or automatic transmission and a vehicle brake, which can be operated by way of external power. The process is characterized in that situations are detected which express the imminent starting of the engine, and then the vehicle brake, particularly the service brake or the parking brake, is operated by way of external power before starting the engine for secure blocking of the vehicle.
It is the essence of the present invention that an imminent starting of the engine be detected. Then, before the engine is started, the vehicle brake, which was first released, is operated by way of external power for secure blocking of the vehicle.
As the result of the automatic operation of the vehicle brake, particularly the parking brake, before the engine is started, the vehicle is secured against rolling away during the starting operationxe2x80x94thus, until the driver""s wish is detected. This measure can be used particularly advantageously also in the case of automatic transmissions with converters, since then, when the engine is started, a forward or reverse driving position may also be engaged, which results in a certain creeping tendency.
The imminent starting of the vehicle can be determined, for example, by way of the unlocking of the vehicle, the opening of the vehicle door, a driver seat occupation detection and/or an operation of the ignition lock or the ignition/start determination. In particular, the operation of a starting or ignition system is closely connected to an imminent engine start.
In the case of automated standard transmissions, there is the additional danger thatxe2x80x94particularly when the selector levers are lockedxe2x80x94, another driving position than the engaged driving position is indicated. Thus, it is possible that, when the driver door is opened, the neutral position of the vehicle is automatically engaged. If the driver then wants to continue to drive, he must first leave the actually indicated driving position and select it again or select another driving position. This generally leads to confusion and is uncomfortable.
In order to avoid this, it can first be checked according to a special embodiment of the invention whether the gear selection device is set to neutral. If this is not so, the gear selection device can be set to neutral before the engine is started or the transmission line can be uncoupled. For example, when the ignition key is rotated to the xe2x80x9cignition onxe2x80x9d position, the vehicle brake can be operated and the clutch can be opened up. This is particularly advantageous in the case of a vehicle with an automated standard transmission wherein when the engine is switched off, the first gear is engaged as an additional safety function.
According to another advantageous embodiment of the present invention, the vehicle brake is released after the engine is started. The release of the vehicle brake can take place as a reaction to the operation of a pedal, for example, an accelerator or brake pedal.
As discussed above, the operation of the vehicle brake takes place by way of external power; that is, the braking pressure or the braking energy to be applied for the vehicle brakexe2x80x94irrespectively of whether it is operated electrically, pneumatically or hydraulicallyxe2x80x94must be generated by way of a corresponding secondary device in the vehicle. This requires energy even before the engine is started, which can be provided only from a battery. For this reason, it is advisable that a service brake not be left activated for too long without any engine operation. A preferred embodiment of the invention is therefore characterized in that the vehicle brake will be released again if, after a certain time period after the activation of the vehicle brake, the engine has not been started. As an alternative, a parking brake can be operated, for which only the operating process itself requires energy; but after the operation, the parking brake is held in a locked condition like a conventional hand brake. Reference is made in this respect to German Patent document DE 196 32 863 A1.
With respect movement of the vehicle without engine power (pushing, towing, staying in a repair shop, etc.), it may also be required to render the service brake inoperativexe2x80x94possibly manuallyxe2x80x94in order to permit the moving of the vehicle in certain situations.
On the whole, the present invention provides a cost-effective, simple, safety and comfort increasing process for starting the engine of a vehicle. In particular, the operating comfort during the vehicle start is increased, without requiring the driver to carry out additional actions before the vehicle start. Furthermore, safety is always ensured by avoiding faulty operations and a rolling away of the vehicle when the vehicle is started.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.